The present invention relates to a vacuum-ultraviolet resist material and patterning method and, more particularly, to a novel polymer compound having in its main polymer chain alicyclic structures with carboxylic acid or carboxylic acid ester moieties.
The mass production of devices with 90-nm pattern resolution by 193-nm lithography technology has already started. To achieve finer device patterning such as 65-nm, 45-nm or 32-nm resolution patterning for higher-density device integration, process and material developments are being rapidly pursued. In particular, extensive development researches are being made to solve problems e.g. etching resistance and pattern edge deformation called line edge roughness (LER) arising in 65-nm resolution patterning or even finer patterning. There are some reports that the introduction of a high proportion of ring structures into a resist polymer contributes to an improvement in etching resistance. Although there are many researches on the mechanism of occurrence of LER, any of the researches does not yet reach a certain cause of LER. It is assumed that LER could be caused due to developer solubility variations and low etching resistance.
As one example of resist resin for 193-nm lithography, a (meth)acrylic ester resin is in wide use. Some reports propose the introduction of a polycyclic compound with e.g. an adamantyl, norbornyl or cholesterol derivative into ester moieties of the (meth)acrylic ester resin for etching resistance improvement. In the case of introducing a high proportion of such polycyclic structures into the (meth)acrylic ester resin for etching resistance improvement, however, the other physical properties of the (meth)acrylic ester resin required for use as the resist material, including solubility in a solvent, adhesion to a substrate and transmittance for excimer laser radiation in a vacuum-ultraviolet range, become deteriorated. The (meth)acrylic ester resin is also still low in etching resistance even when containing a high proportion of polycyclic structures, as compared to a hydroxystyrene resin for 254-nm lithography, and is in need of further etching resistance improvement. On the other hand, a resin having ring structures in its main polymer chain is being under study as an alternative to the (meth)acrylic ester resist resin. Although some reports propose the introduction of cyclopentane or cyclohexane rings to the main polymer chain of the resin for etching resistance improvement, the etching resistance of such a resist resin cannot be improved sufficiently in balance with the other physical properties e.g. solvent solubility, transmittance and resolution contrast.    [Non-Patent Publication 1] Takuya Hagiwara, Yasuhide Kawaguchi, et al., J. Photopolym. Sci. Technol., 16, 557 (2003)    [Non-Patent Publication 2] Francis Haulihan, Will Conley, Larry Rhodes, et al., J. Photopolym. Sci. Technol., 16, 581 (2003)    [Non-Patent Publication 3] Shinichi Kanna, Sanjay Malik, et al., J. Photopolym. Sci. Technol., 16, 595 (2003)    [Non-Patent Publication 4] Takashi, Sasaki, Shigeo Irie, Toshiro Itani, et al., J. Photopolym. Sci. Technol., 17, 639 (2004
Against this backdrop, there has been a demand to create novel polymer compounds having sufficient etching resistance and other required physical properties e.g. transmittance, substrate adhesion and solvent solubility for use as resist materials.